The studies on the self-association of all-trans retinol will be extended to other isomers and derivatives in a variety of solvent systems and under conditions which will permit obtaining enthalpies and entropies as well as free energies of association, to possibly relate these properties to the role of retinol in the visual process. Studies on the binding of retinol binding protein to prealbumin have been initiated, and studies on the behavior of rhodopsin in non-aqueous media are planned.